ESD Clamp Circuit With Assist Node Clamping for Faster Turn-On
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Solution Overview
Problem
The miniaturization of integrated circuits has increased their susceptibility to electrostatic discharge (ESD) events due to thinner dielectric thicknesses and lower dielectric breakdown voltages, leading to potential electronic circuit damage.
Innovation Solution
Incorporating an ESD assist circuit within the integrated circuit that includes a clamp circuit with a PMOS transistor, which clamps a voltage at a specific node to control the gate potential of another transistor, reducing capacitive coupling effects and lowering the turn-on resistance, thereby enhancing ESD performance and robustness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If the integrated circuit is miniaturized to consume less power and provide more functionality, then power consumption is reduced and functionality is increased, but susceptibility to electrostatic discharge increases due to thinner dielectric thicknesses and lower breakdown voltages
Solution Approach 1:
The ESD assist circuit is activated in advance to clamp the voltage at the third node to the first voltage (VDD) before an ESD event occurs. This preliminary voltage clamping ensures that when ESD strikes, the gate potential of the first transistor is already controlled, enabling faster turn-on and reducing the likelihood of damage to the second transistor. The circuit performs the protective action before the harmful ESD event actually impacts the circuit.
2Reliability
If conventional ESD protection circuits are used, then ESD protection is provided, but the transistors turn on slower and with higher resistance, reducing ESD discharge effectiveness
Solution Approach 1:
The ESD assist circuit maintains the gate potential of the first transistor at the same potential as the first node (VDD) by clamping the third node voltage. This equipotential condition eliminates voltage differences that would otherwise cause slower turn-on and higher resistance. By keeping the gate at the same potential as the source during normal operation and during ESD events, the transistor can switch faster and maintain lower on-resistance, significantly improving ESD discharge effectiveness.
3Volume of moving object
If dielectric thickness is reduced to enable miniaturization, then device size is reduced and integration density increases, but dielectric breakdown voltage decreases making the circuit more vulnerable to ESD
Solution Approach 1:
The ESD assist circuit provides beforehand cushioning by clamping the voltage at the third node to prevent excessive voltage buildup that could lead to dielectric breakdown. This protective mechanism is in place before ESD events occur, cushioning the thin dielectric layers from voltage stress. The circuit absorbs and redirects ESD energy through the controlled path provided by the first transistor, preventing the voltage from reaching levels that would cause dielectric breakdown in miniaturized structures.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The ESD assist circuit improves ESD performance by allowing the transistors to turn on faster and stronger, effectively discharging ESD currents and enhancing the overall robustness of the integrated circuit against ESD events.
Implementation Method 1
reducing capacitive coupling effects between the first node and the third node
Implementation Method 2
discharge an ESD current of the ESD event in a forward ESD direction from the second node to the first node
Data Source
AI summary
An electrostatic discharge (ESD) circuit includes an ESD detection circuit, a clamp circuit and an ESD assist circuit. The ESD detection circuit is coupled between a first and a second node. The first node has a first voltage. The second node has a second voltage. The clamp circuit includes a first transistor having a first gate, a first drain, a first source and a first body terminal. The first gate is coupled to at least the ESD detection circuit by a third node. The first drain is coupled to the second node. The first source and the first body terminal are coupled together at the first node. The ESD assist circuit is coupled between the first node and the third node, and is configured to clamp a third voltage of the third node at the first voltage during an ESD event at the first node or the second node.